Fix FUT prices logic, Shareholding residuals, and UI label in Buyback/OFS tabs.

[letssayx]

• Modified get_live_price to fetch futures prices directly from BhavcopyFO instead of DailyDerivativesAnalysis.
• Updated get_shareholding to exclusively fetch from NSE API, failing completely on error, while calculating residuals for Public shareholding dynamically.
• Edited workbench.html to append (100%) to the "Total Outstanding" UI label.

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PR created automatically by Jules for task 12854045025592532615 started by @letssayx

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